IIRFilterNode

The IIRFilterNode interface of the Web Audio API is a AudioNode processor which implements a general infinite impulse response (IIR) filter; this type of filter can be used to implement tone control devices and graphic equalizers as well. It lets the parameters of the filter response be specified, so that it can be tuned as needed.

However, if you need to create an odd-ordered IIR filter, you'll need to use IIRFilterNode. You may also find this interface useful if you don't need automation, or for other reasons.

Once the node has been created, you can't change its coefficients.

IIRFilterNodes have a tail-time reference; they continue to output non-silent audio with zero input. As an IIR filter, the non-zero input continues forever, but this can be limited after some finite time in practice, when the output has approached zero closely enough. The actual time that takes depends on the filter coefficients provided.